Simple JavaScript functions to check if a string is capitalized

Is Capitalized ==

//Assumes that a string is made up of only letters
function isCapitalized(str) {
  var char = str[0]; 
  return char.toUpperCase() == char;
}

Is Capitalized RegEx

//Assumes nothing and can handle numbers and symbols
function isCapitalized(str) {
  var rex = /^[A-Z]/
  return rex.test(str);
}